Air compressor system

ABSTRACT

An air pressure measuring system responsive to pressure between a modulating valve and an air intake of a screw-type air compressor is calibrated in percent of the capacity of the compressor, this air intake pressure varying inversely and linearly with variations in percent of capacity at which the compressor operates. Oil is pumped with the air by the compressor to a receiver-reservoir and then through an oil filter and a cooler back to the compressor. A momentary valve normally connects an oil pressure gauge to the inlet side of the oil filter and, upon manual actuation, connects the oil pressure gauge to the outlet side of the oil filter. A second momentary valve normally connects an air pressure gauge to the receiverreservoir and, upon manual actuation, connects this air pressure gauge to the outlet of an oil separator through which air from the receiver-reservoir passes.

United States Patent Novak 1 1 AIR COMPRESSOR SYSTEM [75] lnventor: Walter M. Novak, Portland, Oreg.

[7 3] Assignee: Rogers Machinery Compenyalnc Portland, Oreg.

[22] Filed: Apr. 5, 1971 211 Appl. 110.; 131,623 [52] US. Cl..., 73/168, 73/115 [51] Int. Cl. 601m 19/00 [58] Field of Search 73/168, 115, 116, 73/112, 117.3; 417/295; 418/88, 85

[56] References Cited UNITED STATES PATENTS 3,191,854 6/1965 Lowler 418/88 2,961,147 11/1960 Osterkamp..... 417/295 3,226,011 12/1965 Gustafson 417/295 2,613,026 10/1952 Banks 417/295 3,002,380 10/1961 Grove 73/168 OIL AIR m PRESSURE I 6 f AFTER BEFORE FILTER FILTER OIL TO BEAR 1 N65 AIR PRESSURE 6 Primary Examiner-Richard C. Queisser Assistant Examiner-Denis E. Corr Attorney-Buckhorn, Blore, Klarquist & Sparkman [57] ABSTRACT An air pressure measuring system responsive to pressure between a modulating valve and an air intake of a screw-type air compressor is calibrated in percent of the capacity of the compressor, this air intake pressure varying inversely and linearly with variations in percent of capacity at which the compressor operates. Oil is pumped with the air by the compressor to a receiverreservoir and then through an oil filter and a cooler back to the compressor. A momentary valve normally connects an oil pressure gauge to the inlet side of the oil filter and, upon manual actuation, connects the oil pressure gauge to the outlet side of the oil filter. A second momentary valve normally connects an air pressure gauge to the receiver-reservoir and, upon manual actuation, connects this air pressure gauge to the outlet of an oil separator through which air from the receiverreservoir passes.

5 Claims, 3 Drawing Figures SOLENOID UNLOADING VALVE CHECK VA LVE r 4' AIR OUT BEFORE FILTER AIR INTAKE MODUL. VALVE 252i??? f 80 5e 7 I I 60 59 64 I 2 COMPRESSOR -1 225;:

$5M,- VALVE 72 HIGH TEMP SW- 1 84 on. LEVEL A 0 Ar OIL FILTER WATER OUT PAIENIEII Jlll 2 4 3 747. 404

FIG. I m

AIR A R PRESSURE PRESSURE 34 .16 I IN 6| 66 76 68 SOLENOID CH AFTER BEFORE AFTER BEFORE JK tQQ if; FILTER FILTER FILTER FILTER A AIR ou-r FILIER 70 I 74 AIR INTAKE MODUL. VALVE PERCE NT CAPACIT Y HIGH TEMP VALVE HEAT 3O SENSING TEMP. REG. OIL

BULB VALVE FILTER 26 WATER 22 OUT WATER lN-nv IO 20 30 40 so so 10 so some CAPACITY AIR CAPACITY PERCENT FIG. 2

OIL FILTER PRESSURE OIL SEPARATOR PRESSURE OIL AIR PRESSURE PRESsURE DEPRESS FOR DOWNSTREAM DEPRESS FOR DO NSTREAM INVENTOR BUCKHORN, BLORE, KLARQUIST 8. SPARKMAN ATTORNEYS AIR COMPRESSOR SYSTEM DESCRIPTION This invention relates to an improved air compressor system, and more particularly to an air compressor system having a percent capacity of operation indicator, a filter oil pressure drop indicator and a separator air pressure drop indicator.

An object of the invention is to provide a new and improved air compressor system. Another object of the invention is to provide an air compressor system having a percent capacity of operation indicator, a filter oil pressure drop indicator and a separator air pressure drop indicator.

A further object of the invention is to provide an air compressor system in which an air pressure gauge responsive to pressure at the inlet of a compressor indicates the percent capacity of operation of the compressor.

Another object of the invention is to provide an air compressor system in which a momentary, three-way valve connects an oil pressure gauge to the inlet and outlet of an oil filter.

Another object of the invention is to provide an air compressor system in which a momentary, three-way valve connects an air pressure gauge to the inlet end of and the outlet end of an oil separator at the outlet of a receiver-reservoir.

In the drawings:

FIG. 1 is a schematic view of an air compressor system forming one embodiment of the invention;

FIG. 2 is a fragmentary, face view of an indicator panel board of the air compressor system of FIG. 1; and

FIG. 3 is a graph showing the ratio of vacuum to percent of capacity of the compressor of the air compressor system of FIG. 1.

Referring now in detail to the drawings, there is shown in FIG. 1 an air compressor system forming one embodiment of the invention and having a control and instrument panel board 12. The air compressor system is equipped with a capacity control means employing an air intake modulating valve 14 controlling the flow of air from an inlet 16 through a filter 18 and a suction line 20 to a constant speed,screw-type air compressor or pump 22. The compressor is driven through a shaft 23 by a motor (not shown). The compressor 22 compresses the air and discharges the compressed air into a receiver-reservoir 24 through line 26. The normal flow of air is out of the reservoir 24 by way of oil separator 28 and service line 30. A check valve 32 is located in service line to prevent bleeding back of the air charged in the service system whem compressor 22 is shut down. Also, an unloading valve 34 is located in service line 30 to discharge air from the receiverreservoir 24 when the compressor 22 is shutdown. Another check valve 36 is located in line 26 between the compressor 22 and reservoir 24 to prevent the compressor 22 from back spinning by line pressure when shut down. A high temperature shutdown switch 38 is also located in line 26 as a safety measure.

Sealing and lubricating oil is introduced into the compressor 22 by an oil pump 40. The oil also absorbs most of the heat generated due to compressing of the air. The oil is cycled with the air from the compressor 22 through line 26 into the receiver-reservoir 24. As the air-oil mixture enters the receiver-reservoir 24, it contacts a baffle plate 42 separating a substantial portion of the oil before reaching the oil separator 28 where the remainder of the oil is removed from the air. The oil is drawn out of the bottom of the reservoir 24 through an oil filter 44 to a heat exchanger 46 where the heat of compression is given up to a flow of circulating cooling water that is controlled by a heat-sensing bulb 48 operating a temperature regulating valve 50.

In the operation of the compressor 22, when the output or line pressure is below the set operating pressure, a butterfly 52 of the air intake valve 14 will remain in an open position. As the line pressure approaches normal, a pilot control system 54 causes the intake valve 14 to move the butterfly 52 toward its closed position thus reducing the rate of compression. When the output pressure reaches the maximum desired, the butterfly 52 is fully closed, and the compressor output is zero.

A percent capacity indicating system 56 responsive to pressure of the air has an indicating unit 59 having a dial 58 calibrated to reflect the percent of compressor capacity at which the compressor is operating at any instant. There is a linear relationship between capacity and pressure of the air as illustrated by the chart of FIG. 3, and the indicating portion 59 is calibrated to reflect this relationship. For remote location of the indicating portion of the gauge, a suitable, known transducing means 60 is provided to register the pressure in the suction line. The transducing means may be a pressure to voltage transducer or a vacuum controlled rheostat that signals the indicating portion 59, which is a voltmeter mounted remotely as on the instrument panel 12. For a not so remote mounting of the indicating unit 59, the unit 59 is a conventional air pressure gauge connected by an air line to the suction' line 20.

The system is provided with means to quickly check the oil pressure before and after the filter 44, thereby having an instant check of the degree of pressure loss in the oil filter 44. A manually operable and momentary oil pressure selector valve 61 and a manually operable, momentary air pressure selector valve 62 have a common connecting line 64 to the receiver-reservoir 24 and the pressure in the receiver-reservoir is normally indicated by both oil pressure gauge 66 and air pressure gauge 68. When a check on the oil pressure drop in the filter 44 is desired, the selector valve 61 is shifted by depressing push button 70 to connect the gauge 66 to line 72 and the pressure at the outlet of the oil filter is indicated on the gauge 66. When the check of oil pressure drop is completed, the button 70 is released and spring 74 returns the valve 61 to connect line 64 to the gauge 66. In a similar manner the threeway air pressure valve 62 is shifted manually by depressing push button 76 to connect gauge 68 to line 78 to cause the gauge 68 to register the air pressure downstream of the oil separator 28. When the push button 76 is released, valve spring 80 resets the valve 62 to block off line 78 and connect the gauge 68 to the line 64 to again indicate the air pressure in the receiverreservoir 24. An oil temperature gauge 82 is located in the suction line to oil pump 40. Also, an air temperature gauge 84 is located between the compressor 22 and the receiver-reservoir 24. An oil level gauge 86 is located in the side of the receiver-reservoir 24. An hour meter 88 is located on panel 12 to record the total number of hours the compressor has run. These gauges help the'operator to maintain proper control of the system.

The percent capacity indicating system 56 continuously gives the percent capacity at which the compressor is operating at each instant, and does so simply by measuring the pressure of the intake air between the valve 14 and the intake of the compressor 22. The momentary valve 61 and the pressure gauge 66 give an easy rapid check on pressure drop of the oil in flowing through the oil filter, and the valve 62 and the pressure gauge give an easy, rapid check on the pressure drop of the air in flowing through the oil separator 28.

I claim:

1. In an improved air compressor system:

' a variable capacity constant speed, positive displacement compressor means having an intake and an outlet,

the compressor means creating a non-pulsating constant volume input flow,

flow regulating means for regulating the pressure of air supplied to the intake inversely relative to the output of the compressor means,

and indicating means responsive to the pressure of the air being supplied to the intake of the compressor means and calibrated in percent capacity at which the compressor means is operating.

2. The improved air compressor system of claim 1 wherein the indicating means is an air pressure gauge.

3. The improved air compressor system of claim 2 wherein the compressor means is a constant speed screw-type pump.

4. The improved air compressor system of claim 3 wherein the flow regulating means is a valve responsive to pressure of air at the output of the compressor means.

5. The improved air compressor system of claim 1 wherein the indicating means comprises pressure to voltage transducing means sensing pressure at the intake of the compressor means and voltage responsive means having an indicator calibrated in percent capac ity of the compressor means actuated by the transducing means. 

1. In an improved air compressor system: a variable capacity constant speed, positive displacement compressor means having an intake and an outlet, the compressor means creating a non-pulsating constant volume input flow, flow regulating means for regulating the pressure of air supplied to the intake inversely relative to the output of the compressor means, and indicating means responsive to the pressure of the air being supplied to the intake of the compressor means and calibrated in percent capacity at which the compressor means is operating.
 2. The improved air compressor system of claim 1 wherein the indicating means is an air pressure gauge.
 3. The improved air compressor system of claim 2 wherein the compressor means is a constant speed screw-type pump.
 4. The improved air compressor system of claim 3 wherein the flow regulating means is a valve responsive to pressure of air at the output of the compressor means.
 5. The improved air compressor system of claim 1 wherein the indicating means comprises pressure to voltage transducing means sensing pressure at the intake of the compressor means and voltage responsive means having an indicator calibrated in percent capacity of the compressor means actuated by the transducing means. 